title: The plant vacuole: emitter and receiver of calcium signals.
abstract: This review portrays the plant vacuole as both a source and a target of Ca(2+) signals. In plants, the vacuole represents a Ca(2+) store of enormous size and capacity. Total and free Ca(2+) concentrations in the vacuole vary with plant species, cell type, and environment, which is likely to have an impact on vacuolar function and the release of vacuolar Ca(2+). It is known that cytosolic Ca(2+) signals are often generated by release of the ion from internal stores, but in very few cases has a role of the vacuole been directly demonstrated. Biochemical and electrophysical studies have provided evidence for the operation of ligand- and voltage-gated Ca(2+)-permeable channels in the vacuolar membrane. The underlying molecular mechanisms are largely unknown with one exception: the slow vacuolar channel, encoded by TPC1, is the only vacuolar Ca(2+)-permeable channel cloned to date. However, due to its complex regulation and its low selectivity amongst cations, the role of this channel in Ca(2+) signalling is still debated. Many transport proteins at the vacuolar membrane are also targets of Ca(2+) signals, both by direct binding of Ca(2+) and by Ca(2+)-dependent phosphorylation. This enables the operation of feedback mechanisms and integrates vacuolar transport systems in the wider signalling network of the plant cell.
authors.affiliation: Plant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences (IAEW), Faculty of Natural Sciences III, Martin-Luther-University of Halle-Wittenberg, 06099 Halle (Saale), Germany. edgar.peiter@landw.uni-halle.de
authors.forename: Edgar
authors.initials: E
authors.lastname: Peiter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D020013:Calcium Signaling; D002147:Calmodulin / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002463:Cell Membrane Permeability; D003600:Cytosol / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D009249:NADP / Q000031:analogs & derivatives / Q000378:metabolism; D010766:Phosphorylation; D059828:Plant Cells / Q000378:metabolism*; D054046:Plant Stomata / Q000378:metabolism / Q000502:physiology; D014617:Vacuoles / Q000378:metabolism*; D000097903:Two-Pore Channels
chemical_list: D029681:Arabidopsis Proteins; D015220:Calcium Channels; D002147:Calmodulin; D002352:Carrier Proteins; D007295:Inositol Phosphates; D009249:NADP; C498240:TPC1 protein, Arabidopsis; D000097903:Two-Pore Channels; C024376:NAADP